Respiratory syncytial virus (RSV), a common cause of winter
outbreaks of acute respiratory disease, results in an estimated
90,000 hospitalizations and 4500 deaths each year from lower
respiratory tract disease among infants and young children in the
United States (1). Outbreaks occur annually throughout the country
(2,3). RSV activity in the United States is monitored by the
National Respiratory and Enteric Virus Surveillance System
(NREVSS), a voluntary, laboratory-based system. This report
summarizes trends in RSV reported by NREVSS for July 1992-June 1997
and presents provisional surveillance results for July-November
1997. These data indicate onset of widespread RSV activity for the
1997-98 season.

Since July 1992, a total of 100 clinical and public health
laboratories in 47 states have participated in NREVSS and have
reported weekly to CDC the number of specimens tested for RSV by
the antigen-detection and virus-isolation methods and the number of
positive results. RSV activity is considered by NREVSS to have
become widespread during the first of 2 consecutive weeks during
which at least half of participating laboratories report any RSV
detections. This definition generally indicates a mean percentage
of specimens positive by antigen detection in excess of 10%.

From July 1992 through June 1997, onset of widespread RSV
activity began each November and continued for a mean of 22 weeks,
until April or mid-May (Figure_1). In most parts of the 48
contiguous states, the peak in activity occurred each year in
January or February; however, in the Southeast, activity peaked as
early as November or December (3). For the reporting period
beginning July 1997, a total of 71 laboratories in 41 states
reported results of testing for RSV. Since the week ending November
7, more than half of the participating laboratories reported
detections of RSV each week, indicating onset of widespread RSV
activity for the 1997-98 season.

Editorial Note

Editorial Note: During the RSV season, health-care providers should
consider RSV as a cause of acute respiratory disease in both
children and adults. Most severe manifestations of infection with
RSV (e.g., pneumonia and bronchiolitis) occur in infants aged 2-6
months; however, children of any age who have underlying cardiac or
pulmonary disease or are immunocompromised are at risk for serious
complications from this infection. Because natural infection with
RSV provides limited protective immunity, RSV can cause repeated
symptomatic infections throughout life. In adults, RSV usually
causes upper respiratory tract symptoms but can cause lower
respiratory tract disease, especially in elderly and in
immunocompromised persons (4-6). Infection in immunocompromised
persons can be associated with high death rates (6).

RSV is a common but preventable cause of nosocomially acquired
infection; the risk for nosocomial transmission increases during
community outbreaks (7). Sources for nosocomially acquired
infection include infected patients, staff, or visitors or
contaminated fomites. Nosocomial outbreaks or transmission of RSV
can be controlled with strict attention to contact-isolation
procedures (7). In addition, chemotherapy with ribavirin may be
considered for some patients (e.g., those at high risk for severe
complications or who are seriously ill with this infection) (8);
RSV immune globulin intravenous (human) is available for prevention
of serious RSV infections in some high-risk infants and children
(9). Vaccines for RSV are being developed, but none have been
demonstrated to be safe and efficacious in infants (10).

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